include/maxscale/gw.h removed.

In a subsequent change, the includes of server/core/*.c will be
cleaned up, and if there is a common set of include files, needed
by most, then a server/core/maxscale/core.h that includes those
will be introduced.

server/modules/authenticator/cdc_plain_auth.c

@@ -26,11 +26,12 @@
  */
 
 #include <maxscale/gw_authenticator.h>
+#include <sys/stat.h>
 #include <cdc.h>
+#include <maxscale/alloc.h>
+#include <maxscale/gwdirs.h>
 #include <maxscale/modutil.h>
 #include <maxscale/users.h>
-#include <sys/stat.h>
-#include <maxscale/alloc.h>
 
 /* Allowed time interval (in seconds) after last update*/
 #define CDC_USERS_REFRESH_TIME 30